Apparatus for stripping film from a drying cylinder



Jan. 7, 1947; J. L-ORMOND 2;413,779

APPARATUS FOR STRIPPING FILM FROM A DRYING CYLINDER Filed Jan. 28,- 1944Patenterl Jan. 7, 1947 APPAnA'rUs FOR s'mrrrme FILM FR M nDnYmGcYLmnEaJohn -I. Ormond, Bense nville, 111., assignor to Kraft-Foods Company, acorporation of Delaware Application January as, 1944, Serial No. 520,141

This invention relates to improvements in the art of stripping filmsfrom drying cylinders. The

2 Claims. (Cl. 159-11) embodiment of the invention herein disclosed isassociated with apparatus employed for-torm-. ing dried films fromliquids or solutions. For example, a liquid containing whey and soyflour may be processed into a very thin, dry film, or web, which issubsequently broken into flake after being carried around somewhat morethan one-half thecircumference of the cylinder), it is doctored from thecylindrical surface of the cylinder by means of a sharp-edged doctorblade.

of stripped material adjacent the doctor blade while also incidentallyremoving the creping from the stripped film;-and in general, it is theobject of the invention to provide an improved method and apparatus forstripping film from drying cylinders.

Other objects and advantages of the invention will be understood byreference to the following specification and accompanying drawing (1sheet) wherein" a selected form of the invention is illustrated.

In the drawing, the 'figureis a more or less schematic sectionalillustration of rotary cylinder dry Incident to such doctoringoperation, the film becomes substantially creped and it has usually beenpermitted to fall by gravity from the doctor blade into a screw conveyoror other receiver. The film is very thin and fragile and is quitedifficult to handle because of the ease'with which it may be broken. Ithas usually been considered impractical to perform any operations on thefilm initstravel from the doctor blade to the receiving conveyor orother device. One great difliculty which has been encountered in thehandling of film of the character indicated in the conventional methoddescribed, has been the tendency of the film doctored fromthe cylinderto fall into surface contact with the dried film remaining on the dryingcylinder and approaching the doctor blade. Such contacting of thestripped film with the unstripped film tends to cause the stripped filmto be again carried into I engagement with the doctor blade withresultant objectionable accumulation of mate'rialat the doctor blade.Also, it may be observed that ac-' cording to the prior art conventionalpractices, the tendency for material to accumulate at the doctor bladeis somewhat aggravated by the fact that the doctor blade inherentlyoperates to crepe the film as it removes the film from the cylinder.Such creping in itself results in a more or less bunching of materialclosely adjacent and in contact with the edge of the doctor blade whereit operates against the cylindrical surface of the cylinder to .stripfilm from the latter.

The main objects of the present invention are to prevent engagement ofthe stripped film with the film-covered surface of the drying cylinder;to effect prompt andsustained removal of the stripped film from thedoctor blade; to

provide means for preventing the accumulation ing apparatus havingincorporated therein the improved film stripping mechanism.

- The apparatus illustrated comprises a pair of cast iron cylinders 5and 6 which are suitably journaled for rotation between supporting sideplates, one of which is represented at I. The rolls 6 and 6 maybe ofcast iron construction substantially 1%" in thickness'and in theneighborhood of 36" in outside diameter. A'pool 8 of the liquid solutionor mixture to be formed into a film and dried, is delivered into thebight of the rolls 5 and 6. The rolls are driven in opposite directionsrelative to each other, as indicated by the arrows 9 and I!) so thattheir upper adjacent surface portions move toward each other anddownwardly. Under such conditions, films II and I! of the liquid will beformed on the surfaces of the cylinders, the thickness or depth of suchfilms being determined largely by the spacing of the cylinders 5 and 6from each other. Suitable means (not herein shown) are usually provided.for effecting adjustment of one of the cylinders 5 or' 6 toward or fromthe other cylinder to permit regulation and control of the depth orthickness of the respective films l I and I2.

To retain the liquid pool 8 near the ends of the rolls 5 and 6,- thereare provided end plates such as indicated at I3, such end plates havingarcuate edges adapted to fit closely against the adjacent surfaceportions of the cylinders 5 and 6. If desired, a coverplate I4 mayextend over the pool 8 of the liquid, such cover plate being supportedby the end walls or plates I 3. The films II and I2 of liquid aregradually dried as they approach the opposite'outer sides of thecylinders 5 and 6. In order to dry the film, the cylinders ,5 and 6 aremade hollow and provided with suitable connections for 'circulatingsteamor any :other heating medium so as to heat the cylinders.

employed (depending upon the particular prod- 3 uct being dried), andthe cylinders have cylindrical walls approximating one and one-quarterinches (1%") in thickness, the outside diameter of the cylinders beingthirty-six inches (36") and their length being eighty-four inches (84")For a whey-soy product mixture in the proportions of five and one-halfpounds of whey (containing five and five-tenths percent (5.5%) solids)?with two and three-quarters pounds (2%#) of commercially processed soyfiour and approrimately sixty-five/one hundredths pound (.65#) of cornstarch, steam at about fifty pounds (50#) per square inch pressure givesgood results when the cylinders are rotated at about 6 R. P. 'M. Undersuch conditions, the dried film will be fairly hygroscopic, containingonly about three and one-half per cent- (3 /2%) of moisture.

The dried film is very thin and may be easily broken into fiakes andpowdered. However, it is sufilciently self-sustaining to permit it tobedoctored from the respective cylinders on which it is formed withoutimmediately flaking the film.

In the conventional practice, a doctor blade, typified by the doctorblades l5 and I6 respectively, is associated with each cylinder in sucha manner as to doctor the film from the surface of the cylinder. Thedoctor blade is preferably a very sharp-edged blade and most films willbe more or less creped incident to the removal thereof fromtherespective cylinders by the doctoring operation.

In order that the film will be adequately dried, it is usually carriedupwardly by the cylinder on which formed, to a point substantially abovethe horizontal plane of the axis of the drying cylinder, the resultbeing that a portion of the surface of the cylinder below the operativeedge of the doctor blade extends horizontally outwardly beyond the pointat which the doctor blade strips the film from the surface of thecylinder. 7

' upper edge of the chute. This arrangement serves to deliver a crepedfilm to the receiving conveyor,

' at the operative edge of the doctor blade, and between such portionsof the doctor blade and the adjacent edge of the chute.

In order to avoid difilculties such as already indicated, and to improvethe, form of the product delivered to the receiving means, the trough orchute arrangement, referred to is removed. In order to guide thestripped film away from the cylinder and away from the doctor blade,there are provided rotatably supported rolls, such as rolls l9 and 20.In the arrangement illustrated, the rolls l9 and 20 are rotatablysupported by suitable arms or hangers, such as indicated at 2|, whichare provided with hooks 22 at their upper ends engaged'overtransverserods 23 which extend between the opposite side frames of the apparatus.The rolls I 9 and 20 are thus supported in such a manner that by theirown weight they maintain surface contact with the adjacent film-coveredsurface of the respective cylinders a short distance below the operativeedges of the respective doctor blades, which'may be carried The filmstripped from the,cylinder by each doctor blade is carried outwardlyfrom the doctor blade and'cylinder over the adjacent roll it or 20 andthence permitted to drop downwardly by gravity into the receiving means.The stripped film portions Ha and l2a intermediate the respective rollsl9 and 20 and the cylinders 5 and B will be positively pulled from thedoctor blades and cylinders incident to the rotation of the respectiverolls. Since the rolls I9 and 20 are driven at substantially the samesurface speed as the cylinders, the film portion I la or l2a will bepulled from the respective doctor blades at substantially the same speedthat the film on the cylinder approaches the doctor blade. Hence, anycreping formed in the films as they are stripped from the cylinders willbe substantially pulled out so that the film delivered to the receivingmeans I! or I8 is a substantially smooth and uncreped film. The uncrepedfilm is advantageous over the creped film in that when flaked or broken,the fiakes or pieces are individually lighter and thinner than thecorresponding portions of a creped film. Furthermore, it has been foundthat the crepe-removing operation has a desirable tendency to lightenthe color of the product.

The stripping rolls, such as l9 and 20, should be located at such apoint that the contacted film on the cylinder is substantially dry andnot subject to being rolled out by the weight of the stripping roll.

Under the operating conditions and for the production of the whey-soyproduct above mentioned, stripping rolls made of wood and 5" indiameter, spaced about four and one-half inches l from the sharp edge ofthe doctor blade (to the point of contact between the roll and cylinder)have been found to give good results. These dimensions are not criticaland may be varied somewhat. I

The drying and stripping apparatus described may be advantageouslyemployed in producing products based on materials other than whey; forexample, buttermilk; skim milk and other milk and non-milk products mayalso be prepared.

The stripping rolls I 9 and '20 may be driven independently of thedrying cylinders and they may be driven at surface speeds which areincreased or decreased relative to the surface speed of the cylinderswith which they cooperate. If it should be preferred that a slightamount of creping be retained in the stripped film, the stripping rollsmay be driven at a surface speed which is slightly slower than thesurface speed of the drying cylinder. Similarly, if it is desired 'toeffect some stretching of the stripped film (where the character of thefilm permits it), the stripping rolls may be driven at a surface speedwhich is slightly more than the surface speed of the drying cylinders.Also, if the characteristics of the film produced permit it, a pressureroll may be associated with each stripping roll so as to more positivelygrip the stripped film for feeding purposes. However, some limitationson the practicality of more forcibly stripping or pulling the film fromthe cylinder exist in view of the frailty of the films and the greatdanger of.breaking the same intermediate the doctor blade and the feedroll. Furthermore, it is not usually desirable that the film be pulledso fast or so hard that it will be removed from the cylinder before itreaches the doctor blade.

Various changes and modifications in the described structure may be madewithout departing from the invention, as defined in the appended claims.

I claim:

1. In apparatus of the class described, the combination of a rotatablydriven drying cylinder, means for forming a film of liquid on saiddrying cylinder, said film being dried during the rotation of thecylinder, the arrangement being such that the dried film is carriedupwardly by the cylinder to'a point above the horizontal plane of theaxis of the cylinder, a doctor blade acting on the dried film at saidpoint above said horizontal plane to strip said dried film from saidcylinder, and a roll engaging and thereby frictionally driven by thefilm covered surface of said cylinder below said doctor blade, said rollbeing adapted to have the film stripped from said cylinder directed overthe surface of the roll whereby the roll is operative, as an incident toits rotation, to pull the stripped film from said doctor blade andcylinder, said roll being of such diameter that its face portion remotefrom said drying cylinder will be spaced horizontally outwardly from theface of said drying cylinder in the horizontal plane of its axis wherebysaid roll is operative to deliver the film in a vertical plane spacedfrom the surface of said cylinder.

2. In apparatus of the class described, the combination of a rotatablydriven drying cylinder, means for forming a film of liquid on saiddrying cylinder, said film being dried during the rotation of thecylinder, the arrangement being such that the dried film is carriedupwardly by the cylinder to a point above the horizontal plane of theaxis of the cylinder, a doctor blade acting on the dried film at saidpoint above said horizontal plane to strip said dried film from saidcylinder, and a roll engaging and thereby frictionally driven by thefilm covered surface of said cylinder below said doctor blade, said rollbeing adapted to have the film stripped from said cylinder directed overthe surface of the roll whereby the roll is operative, as an incident toits rotation, to pull the stripped film from said doctor blade and saidcylinder, hangers having said roll rotatably mounted in their lower endsand pivotally supported at their upper ends at an elevationsubstantially above said roll, said roll being of such diameter that itsface portion remote from said drying cylinder will be spacedhorizontally outwardly from the face of said drying cylinder in thehorizontal plane of its axis, wnereby said roll is operative to deliverthe film in a vertical plane spaced from the surface of said cylinder.

JOHN I. ORMON'D.

